Encryption is commonly used by businesses, government agencies and individuals to render the encrypted data unreadable to anyone except those possessing special knowledge, such as a decryption key. As many data files are stored in the hard disk of computing devices such as a personal computer, harddisk encryption is used to prevent unauthorized access to confidential or restricted files on the computing device. Typically, the entire hard disk is decrypted upon successful system boot with the user's access code. Once the computing device is in a working state (e.g., the Advanced Configuration and Power Interface (ACPI) state S0) and completely booted, unauthorized access may nevertheless occur as all files on the hard disk are decrypted. For example, when the computing device is left unattended, an attacker may gain access to the computing device remotely. To protect against such unauthorized access, users tend to resort to password-protecting sensitive files.
However, this approach is not without its problems. For example, a password may be easy for the user to remember but not strong enough and hence prone to be cracked by an attacker. As another example, the user may select, remember or exchange a password via an insecure email. Besides, from the perspective of user-friendliness, it is not optimal that the user needs to remember and manually enter the password.
Near Field Communication (NFC) is a standards-based connectivity technology that establishes wireless connection between two devices in close proximity of each other, typically in the order of a few centimeters. NFC allows users to transfer information by touching, or tapping, one device with another device. As with proximity card technology, NFC uses magnetic induction between two loop antennas located within two NFC-enabled devices that are within close proximity of each other, effectively forming an air-core transformer. The act of bringing one NFC-enabled device to close proximity of another FC-enabled device with or without the two devices physically contacting each other, is referred to as an “NFC tap” or “one tap” operation hereinafter. With an NFC tap operation, a user can conveniently perform a variety of tasks, including mobile payment, secure login, wireless pairing and implementing a user-friendly mechanism for triggering peer-to-peer data exchange between two NFC-enabled devices.
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